Reinforced concrete (RC) structures built in China between 1912 and 1949 exhibit unique performance characteristics due to significant differences between their historical and modern reinforcement. These structures represent valuable architectural heritage, and their longevity necessitates effective preservation strategies. However, a paucity of information hinders the development of targeted conservation plans. To comprehensively understand the mechanical properties of these historical RC structures, this study investigates the historical reinforcement, focusing on its shape characteristics, material properties, and bond strength. Six distinct types of rebar from this period were collected and subjected to tensile and pull-out tests to determine material properties (e.g., tensile strength) and bond-slip behavior, respectively. Metallographic analysis, examining grain boundaries, inclusions, and defects such as non-metallic inclusions, provided insights into material purity, structural integrity, and potential failure mechanisms. Examination of the historical steel rebars revealed the absence of overt nonmetallic inclusions. Rebar SP-22 exhibited a higher pearlite content. Spiral rebars did not show a clear yielding stage prior to failure. The shape of the steel rebars significantly affected bonding performance.